Adding holes to plates for added strength
Adding holes to plates for added strength
(OP)
Hello guys, im still relitivly new in the engineering world and im just getting started with some of my classes however i got a few quick questions for ya guys
At the gym i see excerise equipment that has what appears to be 1/2" plate supporting the seats and they have a series of different sized holes in a line on it.. im not sure if it was for aesthetics or if it was also some added structure.. i was told before that some tubing is stronger then sq bar because of the added walls.. im not to sure about that statement because it appears when i do some standard beam calcs out of the mechinary's handbook the inertia of solid bars seem to be larger
i was just curious about this, i know how triangles strenthen just about anything you do, but circles are another very rigid structure too right? simular to what an arch would do?
At the gym i see excerise equipment that has what appears to be 1/2" plate supporting the seats and they have a series of different sized holes in a line on it.. im not sure if it was for aesthetics or if it was also some added structure.. i was told before that some tubing is stronger then sq bar because of the added walls.. im not to sure about that statement because it appears when i do some standard beam calcs out of the mechinary's handbook the inertia of solid bars seem to be larger
i was just curious about this, i know how triangles strenthen just about anything you do, but circles are another very rigid structure too right? simular to what an arch would do?






RE: Adding holes to plates for added strength
RE: Adding holes to plates for added strength
RE: Adding holes to plates for added strength
It is not uncommon to see beams being modified as you have noticed. For example, castellated steel beams will often deepen the beam cross-section and increase the members stiffness (I value), while making a reduction of the shear capacity because the web has been modified. If the steel beam is governed by deflection checks and has plenty of capacity in shear than castellated beams will generally being a viable option (fabrication costs permitting).
Another example is precast prestressed concrete beams. These beams may be rectangular cross sections with polystyrene void formers cast in the center of the cross section. Because the units are prestressed they will have a higher shear capacity (compressive stresses) so a reduced shear area may be viable, but importantly they increase the I:A ratio, so the beam will deflect less under self weight.
RE: Adding holes to plates for added strength
RE: Adding holes to plates for added strength
http://www.grunbauer.nl/eng/waarom.htm
RE: Adding holes to plates for added strength
It is better to consider the question on the basis of what makes sense, rather than what you were told. The inertia of a solid bar is greater than that of a hollow tube with the same exterior dimensions. For the same yield strength, the solid bar is stronger. The strength of the tube is equivalent to the strength of the solid bar less the portion removed.
Perhaps what you were told is that the strength per unit weight is greater for the tube than for the solid bar. I would agree with that.
BA
RE: Adding holes to plates for added strength
So we drill big holes in the web. The remaining material is enough to react the shear forces.
However in the case of gym gear I suspect aesthetics has far more to do with it.
Cheers
Greg Locock
I rarely exceed 1.79 x 10^12 furlongs per fortnight
RE: Adding holes to plates for added strength
RE: Adding holes to plates for added strength
RE: Adding holes to plates for added strength
RE: Adding holes to plates for added strength
RE: Adding holes to plates for added strength
I could see, however, holes being added to alter the flexibility or stiffness for reasons of ductility.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Adding holes to plates for added strength
Dimple dies used a lot in auto applications, reduce weight and increase I.
RE: Adding holes to plates for added strength
intersting.. tubes are stronger in torque applications? why would that be? does it allow for more radial deflection before failing?
RE: Adding holes to plates for added strength
RE: Adding holes to plates for added strength